Ok, this problem has me stumped. Sometimes, my 2002 i35 won't go into gear when i shift into "D", but I can move it over to "1" (manual mode) and it will take off just fine. Then, half a block down the street, I can put it back into "D" (automatic mode) and everything is fine. It doesn't shift hard or bad, and it only does it sporadically. I have also recently changed the transmission filter and replaced the fluid that is lost when dropping the pan. Does anyone have an idea of what I should look for?